Electric circuit breaker



/ April 6, 1943.

C. THUMIM ELECTRIC CIRCUIT BREAKER Filed June 28, 1940 5 Sheets-Sheet lInventor: Carl Thumim His Attorney.

April 6, 1943. c. THUMIM ELECTRIC CIRCUIT BREAKER Filed June 28, 1940 3Sheets-Sheet 2 L1 1\/c:T \tOT. Cari Thumim, b fi 6. jam 4 4 HisAttovw'xe April 1943- c. THUMIM ELECTRIC CIRCUIT BREAKER 3 Sheets-Sheet3 Filed June 28, 1940 Fig 5.

Inventor". Carl Thumirn by His Attorney.

Patented Apr. 6, 1943 ELECTRIC CIRCUIT BREAKER Carl Thurnim, Yeadon,Pa., assignor to General Electric Company, a corporation of New YorkApplication June 28, 1940, Serial No. 343,002

14 Claims.

My invention relates to electric circuit breakers and operating systemstherefor and more particularly to operating systems for effectinghighspeed operation of circuit breakers of the fluidblast type.Specifically, my invention is an improvement on the circuit breakeroperating system disclosed and claimed in the copending jointapplication of myself, E. J. Frank and A. C. Boisseau, Serial No.317,564, filed February 6, 1940, and assigned to thesame assignee as thepresent application.

In an effort to eliminate the fire hazard, circuit breakers have beendesigned which do not utilize oil or other inflammableliquid forarc-extinguishing purposes but instead employ a blast of fluid,preferably air or other gas, to extinguish the arc formed both when thecircuit is broken between the relatively movable contacts of the circuitbreaker and also during the closing operation of the circuit breaker toprevent the formation of any are at that time. Such fluid-blast circuitbreakers provide numerous operating and structural advantages for manyapplications but the problem of providing a suitable control oroperating system, particularly when high-speed operation is desired,furnishes considerable difii culty.

The value of any circuit breaker lies in its ability to interrupt thecircuit at the proper time and in the proper manner. Therefore, withouta satisfactory control or operating system, the value of a circuitbreaker, however efficient and reliable, is largely lost for, if controlof the circuit breaker in the manner intended is not obtained, manyundesirable conditions may result.

Since a gas-blast circuit breaker depends upon a blast of gas, such asair, for arc-extinguishing purposes, it is essential that such blast ofair occurs simultaneously with or prior to the separation of thecontacts. In some of the priorart arrangements, it was possible for thecontacts to separate without the existence of the necessaryarc-extinguishing blast, and often considerable damage resulted not onlyto the circuit breaker, itself, but to associated apparatus. It would bedesirable to provide a control and operating system for a gas-blastcircuit breaker in which separation of the contacts cannot ordinarilytake place until a blast of gas, such as air, for arc-extinguishingpurposes exists at the contacts when an arc is drawn therebetween.

Ordinarily, it is desirable to be able to open the circuit breakercontacts for interrupting the circuit in as short a time as possibleafter the condition which initiates the opening movement occurs. This isno less true of gas-blast circuit breakers than of any other type and,accordingly, it is necessary that high-speed valves for controlling thegas blast be provided.' It would be desirable to provide valves forgas-blast circuit breakers which may be operated either manuallyorautomatically with a relatively small force and which not only operatewith very high speed but which are positive and efilclent in theiraction.

Accordingly, it isan object of my invention to provide a new andimproved operating system for a fluid-blast circuit breaker whereinrapid, positive, and efllcient high-speed interruption may be obtainedcombined with reliability, economy, and low first cost.

It is another object of my invention to provide a new and improvedoperating and control system for a circuit breaker of the gas-blast typein which a blast of gas, such as air, is insured adjacent the contactsprior to any separation between such contacts of the circuit breaker.

It is a further object of my invention to provide a new and improvedblast valve for the operating system of a gas-blast circuit breaker.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to theaccompanying drawings in which Fig. 1 is a schematic diagram partly insection of an operating and control system for a gas-blast circuitbreaker embodying my invention, Fig. 2 is a sectional view of asolenoidoperated valve shown schematically in Fig. 1, Fig. 3 is asectional view of the blast valve and associated apparatus shownschematically in Fig. 1, Fig. 4 is a sectional view of a pneumaticallycontrolled tripping means and interlock therefor shown schematically inFig. 1, and Fig. 5 is a sectional view taken on line 55 of Fig. 4.

Although my invention is applicable to polyphase or single-phase circuitbreakers, I have illustrated my invention schematically in Fig. 1 asapplied to a polyphase circuit breaker ill, only the structureassociated with one set of contacts for one pole Illa of the circuitbreaker being shown since the other poles of the circuit breaker areidentical. Where I have illustrated any operating mechanism for thevarious phases or poles which are identical for each phase or pole, suchparts are hereinafter characterized by the same reference numerals withthe subscript a, b, or c,

dependlng upon the particular phase or pole of the circuit breaker.Circu t breaker in is illustrated as of th cross gas-blast ty e and thepole Illa thereof is illustrated as comprising a station ary contact Haand a movable contact 12a arran ed to be o erated so as to dr w an arcin arc chute 43a. Contacts Ila and Ho are arranged to be connected withsuitable line term nals, n t shown. The fixed contact Ha is providedwith spring-pressed contact fingers Ma and longer arcing contact fin ersI4'a. wh le movable contact l2a is provided with an arcing tip l2'a sothat. when the contacts separate, an arc occurs between arcing tins i4'aand l2'a. Immediately after separation of the contacts. one terminal ofthe arc is transferred by a blast of fluid. su h as air, flowing inconduit I5 from Contact fingers l4a to the contact i4"a which is rovidedwith a tip of arc-resistant metal. The fluid blast from conduit uponopening of the circuit breaker drives the are into the arc chute 13::against the edges oi a lurality of partitions 16a in the arc chute,which partitions are transverse to the arc gap and the ends of whichextend close to the path 01 movement of the arcing tip l2a of movablecontact Ho. The circuit breaker 10, only pole Ma 01' which is shown, isillustrated by way of example in order to describe my new and improvedoperating and control system. This circuit breaker, briefiy describedheretofore. is not my invention but is described and claimed in thejoint application of David C. Prince. William l Rankin, and Wilfred F.Skeats, Serial No. 303.12 filed November 6, 1939, now Patent No.2.284342, issued June 21, 1942, and assigned to the same assignee as thepresent application.

Each of the movable contacts of the various poles or phases of circuitbreaker 10, such as Il a which alone is illustrated, is connected toindividual operating rods l1a, Nb, and He, respectively. Theseindividual operating rods I111, Nb. and 110 are respectively connectedto one end of suitable levers 18a, 18b, and IE0, each having the otherends thereof provided respectively with cross heads i9a, I91), and Hearranged to slide in cross-head guides 20a, 20b, and 20c. Suitablebuffers 2la, 21b, and He, respectively are provided for each of thelinks 18a, 18b, and 180 to cushion the closing movement of the operatingmechanism and associated circuit breaker Ill. Each of the links 18a,18b, and I80 has an intermediate point thereon pivotally connected toone end of bell cranks 22, 23, and 24, respectively. which, in turn, arep votally mounted on fixed supports 25, 26. and 21. In order that themovable contacts 12 associated with all of the poles of circuit breakerin are simultaneously actuated. bell cranks 22, 23, and 24 areinterconnected by a horizontally reciprocating operating rod 28.

Any suitable means may be provided for producing relative movementbetween the contacts H and 12 of circuit breaker In. In Fig. I, I haveillustrated energy-storage means comprising opening spring 29 andbalancing spring 30 for supplying the force required to produce uniformhigh-speed opening of circuit breaker l0. Opening spring 29 is arrangedto operate rod 3| which engages with roller 32 attached to an extension24' of bell crank 24. Similarly, balancing spring 30 is connected to anextension 24" of bell crank 24. When these springs are charged as shownin Fig. 1, they tend to cause clockwise rotation of bell crank 24 and,consequently, also of bell cranks 22 and 23 which are connected togetherthrough 76 horizontally reciprocating operating rod 23 which movestoward the right.

In order to close the contacts of circuit breaker In as well as tocharge the energy-storage means comprising opening spring 29 andbalancing spring 30, I provide a fluid motor 33 comprising a cylinder 34in which is reciprocally mounted a piston 35 operatively connected to aforce-transmitting rod 36 arranged to engage with a trip- Ireethrust-transmitting linkage generally indicated at 31. Thisthrust-transmitting linkage 31 has one end thereof connected to the bellcrank 23 so as to cause movement of rod 28 and bell cranks 22 and 24 toclose the respective contacts H and I2 of circuit breaker Ill.

The fluid motor 33 is shown in Fig. l at the instant when circuitbreaker ID has just been completely closed. Since this fluid motor 33 isused only to close circuit breaker l0 and charge opening springs 29 and30, it is desirable to provide suitable means for returning piston 35 toits initial position at the left-hand end of cylinder 34 after theclosing operation is completed. Accordingly, I have shown a suitablereturn spring 38 mounted in a housing 39 supported by cylinder 34.Suitable ports 40 in housing 39 allow air in cylinder 34 to the right ofpiston 35 to escape when circuit breaker I0 is being closed.

The trip-free thrust-transmitting structure generally indicated at 31can be of any suitable design, the one shown by way of examplecomprising a main toggle 4 I 42 including a roller 43 which coacts withthe torque-transmitting rod 36 associated with piston 35. The togglelink 4| is pivotally connected at one end to a lever 44 supported on afixed pivot 43. The toggle link 42. on the other hand, is connected at46 to one end of a lever 41 supported on a fixed pivot 48. The other endof lever 41 is connected through link 49 to bell crank 23. The pivot 50of the toggle link 4| is normally held fixed by a suitable trippingmeans including an extension 44' on lever 44 supporting a roller 5|which coacts with tripping latch 52 pivotally mounted at 52'. When thetoggle 4l--42 is straightened at its knee joint; 53 byforce-transmitting rod 36, the lever 41 is rotated about its fixed pivot48 in a clockwise direction to cause rod 28 to move toward the left toassume the position shown in Fig. 1 when the circuit breaker is closed.When the latch 52 is moved out of restraining engagement with respect toroller 5|, lever 44 is free to pivot in a counterclockwise direction.The toggle 4 l-42 is then no longer in thrust-transmitting position andis free to collapse, permitting movement towards the right of rod 23under the bias of the energystorage means comprising opening spring 23and balancing spring 30.

In Fig. 1, the trip-free thrust-transmitting linkage 31 is illustratedin a restraining or closed position with respect to rod 28. In thisposition, the knee joint 53 of toggle 4l42 is overset and engages a stopmember 54. The linkage is. thereby, effectively locked in this positionwith respect to any opening thrust tending to move rod 28 toward theright as long as the pivot 50 of toggle link 41 is held fixed by theabovedescribed tripping means. When latch 52 of the tripping means nolonger restrains link 44 and, hence, also pivot 50, the former rotatesin a counterclockwise direction under the influence of the reactingforces tending to cause opening movement of horizontally reciprocatingrod 23. When the toggle 4|-42 has collapsed and the lever 41 is rotatedin a counterclockwise direction, opening of circuit breaker l6 resultsthrough upward movement of operating rods 11a, 11b, and Ho respectively.

Because of the high opening speed of circuit breaker 10, it isdesirableto provide cushioning means for retarding the opening movementso as to prevent any damage to the moving parts thereof. Accordingly, Ihave shown a suitable dashpot 65 connected to a pivotally mounted link66 having a roller 51 at one end thereof which is arranged to engagewith a suitable cam surface 56 provided on bell crank 22. The dashpot 55and cam surface 58 may be so designed that any desired openingcharacteristic is obtained. For example, it may be desirable to sodesign cam surface 58 as to provide an arrangement similar to thatdisclosed and claimed in United States Letters Patent 1,904,539, grantedApril 18, 1933, upon an application of Sigwart Ruppel.

In order to operate fluid motor 33 and to provide a blast of gas, suchas air, in the arc chutes l3 adjacent contacts H and 12 of circuitbreaker to, I provide a source 59 of gas under pressure. Fluid motor 33is connected to source 59 of gas under pressure through conduit 60,solenoid operated closing valve 61 and conduit 62. The cross gas blastfor arc-extinguishing purposes in arc chutes I3 is also obtained fromsource ,50 through-conduit 63, blast valve 64, and conduit I5. It willbe understood by those skilled in the art that a single blast valve 64controls the flow of gas to all the poles of the circuit breaker l6including pole a, and additional conduits I5, not shown, would beprovided for the other poles or phases of circuit breaker I0.

Solenoid-operated closing valve 6|, shown schematically in Fig. 1, isdisclosed in detail in Fig. 2 as a valve of the balanced pressure typesimilar in some respects to the valve disclosed and claimed in UnitedStates Letters Patent 1,912,024, granted May 30. 1933, upon anapplication of Werner Uebermuth and assigned to the assignee of thepresent application. Solenoid-operated closing valve 61 is a high-speedvalve with high flow efficiency so constructed and arranged as tooperate in any position and comprises a valve body 65 in which isreciprocally mounted a piston-operated valve member 66 arranged tocooperate with an annular valve seat 61. Valve member 66 is suitablyguided in its reciprocal movement by a plurality of ribs 65 formedintegrally with valve body 65. A piston 68 mounted in a cylinder 69formed in valve body 65 is operatively connected to valve member 66. Anadditional guide means comprising fluted member 16 is provided forsolenoid-operated closing valve 61 which cooperates with a cylindricalsurface 11 formed in valve body 65. A plurality of openlugs .12 areprovided in valve body 65 so that, when valve member 66 is in the closedposition shown in Fig. 2 in engagement with annular valve seat 61,cylinder 34 of fluid motor 33 is vented to atmosphere through conduit 66and openings 12 whereby piston return spring 36 may readily returnpiston 35 of fluid motor 33 to its initial position at the left-hand endof cylinder 34 of Fig. 1.

When valve member 66 is moved away from annular seat 61 so as to providea direct pas- Sage between conduits 60 and 62. valve member 66cooperates with cylindrical surface H, thereby to prevent the escape ofany gas or air to the atmosphere through openings 12. The areas ofpiston 66 and valve member 66 are proportioned in such a manner that theforces due to fluid pressure tend to keep the valve member 66 tight- 1yagainst annular seat 61 under normal conditions, as shown in Fig. 2.Under special conditions, when there is no fluid pressure in source 69,as at the start of filling thereof, a suitable light spring 13, isprovided to hold the valve closed.

To obtain maximum opening speed of solenoid operated valve 61, it isdesirable to minimize the clearance volume in cylinder 69 below piston68 so that gas under pressure contained therein may be evacuated in ashort interval of time as will be described hereinafter. A small passage16 is provided through valve member 66 and piston 66 to interconnectcylinder. 69 with the pressure source 56 through conduit 62, thereby tobalance the forces due to gas pressures under steady state conditionswhich tend to cause movement of valve member 66 whereupon substantiallythe only force tending to hold valve member 66 against seat 61 is springmember 13.

In order to open solenoid-operated closing valve 61 so as tointerconnect conduits 60 and 62, a pilot valve 16 of relatively largediameter is provided to release the pressure in cylinder 69 below piston68 rapidly, thereby unbalancing the forces acting on the piston-operatedvalve member by reducing the force acting on piston 68 substantially tozero so that the downward force on valve member 66 is sufilcient tocause valve member 66 to snap open and close 011 the openings 12 by thetight fit between cylinder 66 and cylindrical surface 1|. Since fluidcan pass through pilot valve 16 considerably faster than through opening15 which is relatively small, no pressure can build up below piston 66and valve member 66 will remain open until pilot valve 16 is closed.

It will be understood by those skilled in the art that the operation ofpilot valve 16 requires considerably less force than would be requiredto move valve member 66 directly. Pilot valve 16 is normally held inclosed position by spring means 11 acting through lever 18 pivoted at16. In order to open pilot valve 16 and, consequently, to open closingvalve 61, a solenoid is provided to overbalance the spring means '11which normally holds pilot valve 16 in the closed posi tion. Thereuponpilot valve 16 is immediately caused to open by the force due to therelatively high air or gas pressure contained in cylinder 69 belowpiston 68. Upon deenergization of solenoid 80, spring means 11 closespilot valve 16 and, as soon as sufilcient gas has passed through smallopening 15 to balance the forces due to gas pressures acting on thepiston 68 and valve member 66, spring means 13 causes valve member 66 toengage valve seat 61 and interrupt the flow of gas from conduit 62 toconduit 66. Since the volume of cylinder 69 below piston 66 i very smallthe pressures are balanced in a short interval of time to cause rapidclosing of valve member 66. Solenoid 80 may be energized from anysuitable source of electrical energy when it is desired to close circuitbreaker Ill. It will be understood by those skilled in the art that theabove-described solenoid-operated valve operates at very high speed andhas a high flow efiiciency.

The cross gas blast for arc-extinguishing purposes in the arc chutes 13of circuit breaker I0 is also obtained from source 59 through blastvalve 64 as mentioned above. This blast valve 64 and associatedapparatus is only schematically shown in Fig. 1 in the interest ofclearness and simplicity in the drawings, but the details thereof areshown in Fig. 3. Referring now to Fig. 8, I have illustrated blast valve84 as comprising a streamlined valve member 8| which allows fluidpressure from source 58 and conduit 88 to pass to conduit I6 withmaximum ilow emciency. Valve member 8| cooperates with a replaceablevalve seat 8| which i mounted in a casing 82 enclosing a cylinder 88within which piston 84, operatively connected to valve member 8| throughconnecting rod 85, reciprocates. Connecting rod 85 is arranged tocooperate with a valve guide 88 to guide the opening and closingmovements 01 valve member 8|. A spring member 81 placed between valveguide 86 and piston 84 normally tends to hold valve member 8| in aclosed position against valve seat 8|. Since blast valve 84 operate withhigh speed, suitable cushioning means are necessary and, in Fig. 3, Ihave disclosed a metallic striking plate 88 behind which is mounted asuitable butler 88 to cushion and limit the opening movement of valve8|.

The area of piston 84 is larger than that of valve member 8| so that, ifgas under the same pressure as that acting on valve member 86 wereadmitted to cylinder 88 below piston 84, valve member 8| would be movedaway from its seat 8| and thus interconnect source 58 and conduit I5.Accordingly, I provide a pilot-operated balanced pressure valve 88comprising a piston-operated valve member substantially identical withthe piston-operated valve member of solenoidoperated closing valve 6|illustrated in Fig. 2 and described in detail above for controlling theapplication of a force due to gas pressure entering cylinder 83 belowpiston 84. When balanced pressure valve 88 is opened, fluid from source58 flows through the relatively large filling passage iii to act on thelower side of piston 84, thereby overcoming the force due to the gaspressure acting on valve member 8| and the force exerted by spring 81 soas to cause valve member 8| to snap open against striking plate 88. Thevolume of cylinder 83 below piston 84 when val e member SI en ages seat8| is maintained at an absolute minimum so that gas pressure frompassage 8| may become efiective immediately when balanced pressure valve88 is opened whereby very highspeed opening of valve member 8| isobtained.

Since the piston-operated valve member of balanced pressure valve 88 issubstantially identical with the piston-operated valve member of closingvalve 6| illustrated in Fig. 2, no further description thereof will beincluded here. However, the corresponding parts of the balanced pressurevalves of Figs. 2 and 3 are designated by the same reference numerals,those in Fig. 3 being marked with a prime.

It will be observed by those skilled in the art that, when pilot valveI6 i opened, balanced pressure valve 88 is actuated which, in turn, actsas a pilot valve for the main piston-operated valve including valvemember 8|. Thus, a relatively small force for opening pilot valve 16'causes opening of valve member 8| of blast valve 64.

Pilot valve I6 is normally held in the closed position by spring 82acting through lever 88 pivotally mounted at 84. A solenoid 85 isprovided for overcoming the eiTect of spring 82 and allowing pilot valve16' to open with the consequent opening of blast valve 64. Solenoid 85is connected to lever 86 also pivotally mounted at 84 and provided witha suitable pin 81 arranged to engage with an extension 88' of lever 88so that, when solenoid 85 is energized, levers 88 and 88 are rotated ina coimterclockwise direction pilot valve I8 is opened. A suitable spring88 is provided to move lever 88 to the position shown when solenoid 88is unenergized. It will be understood by those skilled in the art thatsolenoid 88 will be energized in response to predetermined abnormalelectrical conditions which require tripping of circuit breaker I8.

As will be described in detail hereinafter, pilot valve 16 is alsomechanically operable in response to the position or the contacts ofcircuit breaker I8 so as to provide a timed closing gas blast as well asto time the opening arc-extinguishing gas blast and, accordingly, alever 88 i provided pivotally mounted at 84 including a roller I88arranged to engage with an extension 88" on lever 88. A suitableoperating rod I8I connected to lever 88 is arranged to causecounterclockwise rotation thereof as well as of lever 88 to open pilotvalve I6 through the interaction 01 roller I88 with extension 88" oflever 88. Under these conditions, spring 88 prevents lever 86 fromrotating.

Occasionally, it is desirable to control the circuit breaker manuallyand, to this end, pilot valve I6 may be operated by a manual operatingforce applied to cable I82 attached to lever 88.

In order to prevent damage to the circuit breaker and associatedapparatus, it is essential that a blast of gas be provided adjacent thesenarating contacts simultaneously with the opening movement of thecircuit breaker or preferably prior to such opening movement. I haveprovided a pneumatic tripping arrangement wherein tripping of circuitbreaker I8 and opening movement thereof cannot occur until blast valve64 is at least partially open and the condition of the fluid pressuresource is such as to allow satisfactory interruption of the circuit.

It will be observed from Fig. 1 that circuit breaker I8 cannot be openedunless latch 62 is rotated so as to release lever 44. Accordingly, Ihave provided a pneumatic arrangement generally indicated at I 83 forrotating latch 52 so that circuit breaker I8 may open only after blastvalve 84 is open. This pneumatic arrangement I88 comprises a valve I84,conduit I85, tripping valve I88, conduit I85, and pneumatic trippingmeans generally indicated at I81 and illustrated in detail in Figs. 4and 5.

Whenever opening of circuit breaker I8 is initiated either manuallythrough cable I82 or electrically upon energization of solenoid 85,lever 86 is caused to rotate in a counterclockwise direction about pivot84 so asto open pilot valve 18' and, consequently, also the mainpiston-operated blast valve including valve member 8|. Valve I84 isprovided in order to insure that blast valve 84 is at least partiallyopen before circuit breaker I8 is tripped. This valve I84 is mounted onthe lower end of piston 84 of blast valve 64 and closes the end ofconduit I85 when valve member 8| is in the position shown in Figs. 1 and3. However, when piston 84 has traveled a very short distance to movevalve member 8| away from cooperating valve eat 8 I valve I84 iswithdrawn from the end of conduit or passage I85 50 that fluid underpressure may enter therein.

Tripping valve I86 is illustrated as comprising reciprocally mountedplunger I88 pivotally connected to lever 86 at I88 so that, whenever thelatter is rotated to open blast valve 64, tripping valve I86 is alsoopened to interconnect conduits I85 and I85. Tripping valve I88 isprovided with an opening II8 through which conduit I85 may that suchtripping would be unsafe.

' as shown inFigs.1 and 3.

As soon as valve I04 is opened, insuring opening of blast valve 64, andwith valve I06 having been previously opened, fluid under pressure isadmitted totripping means I01 shown in detail in Fig. 4. This trippingmeans comprises a housing III including a cylinder II2 within which isreciprocatingly mounted a piston II3 operatively connected to a trippingplunger I I4 provided with spring means II5 opposing the force due tothe fluid pressure admitted through conduit I05 and acting on pistonII3. Preferably, cylinder I I2, which may comprise an impregnatedbushing so as to require no further lubrication, is designed to have assmall a volume as possible to increase the speed of operation oftripping plunger II4- when fluid pressure is admitted thereto. The endof tripping plunger I I4 is arranged to engage with tripping finger I I6mounted on the same shaft 52' as latch 52 so as to cause rotation oflatch 52 and release of the trip-free mechanism 3?, whereupon circuitbreaker I 0 may open at high speed by virtoe of the energy supplied byopening spring 29 and balancing spring 30.

I It would be desirable to prevent tripping of cir cuit breaker I0 if,for any reason, the pressure in source 59 were below a, predeterminedvalue so Accordingly, I have provided an interference interlock,generally indicated at H! in Fig. 1 and shown in detail in Fig. 5, whichprevents movement of tripping finger H6 and, consequently, preventsopening of circuit breaker I0. This interference interlock III comprisesa cylinder I I8 connected through a suitable conduit II9 to fluidpressure source 59. A suitable piston I20 is arranged to reciprocate incylinder II 8. This piston is connected to rod I2 I, having an enlargedportion I2I at the other end thereof, which is slidable in a cooperatingguide I22. A suitable spring means I23 is provided acting on theenlarged portion I2I' of rod I2I to oppose the force due to fluidpressure in cylinder I I8. Whenever the fluid pressure in source 59 isabove a predetermined minimum amount, piston I20 is moved suflicientlyfar to the right, as indicated in Fig. 5, against the force of springmeans I23 50 that the rod I2I is adjacent tripping finger I I2, allowingfree movement thereof. If, for any reason, however, the pressure insource 59 should fall below this predetermined amount, spring means I23will cause the enlarged portion I2I' of rod I H to move to the left soas to interfere with free movement of tripping finger I I6 and toprevent rotation thereof and consequent tripping of circuit breaker I0.Adjustable means I 24 are provided to vary the tension of spring I23 and,thereby adjust the predetermined minimum pressure below which interlockIII becomes effective. It may be desirable to remove the electricalcontrol of circuit breaker I0 50 that neither closing nor openingthereof can be accomplished when the pressure of source 59 is inadequatefor proper circuit interruption. To this end, I may provide alow-pressure switch, not shown, similar to that disclosed and claimed inmy copending joint application, Serial No. 317,564, referred to abovewhich will render all electrical controls of circuit breaker I0ineffective when the pressure of source 59 falls to a predeterminedvalue.

Mechanical operation of pilot valve 16' in response to the position ofthe movable contacts I2 of circuit breaker I0 to provide a blast of airor gas during the closing movement of the circuit breaker as well as totime the opening arc-extinguishing gas blast is obtained by means of acam I25 pivotally mounted on fixed support 21 and rotatable with bellcrank 24. This cam I25 is provided with a suitable cam surface to engageroller I20 and cause movement of operating rods IN and IN when openingof circuit breaker I0 is initiated either manually through cable I02 9relectrically by means of solenoid 95. Whenever pilot valve 16' isopened, resulting in the opening of blast valve 64 and release of thetrip free thrust-transmitting mechanism 31 there occurs a clockwiserotation of bellcranks 22,23, and 24 as well as of cam I25. Pilot valveI6 and, consequently, blast valve 64 are held open by cam I25 for a.predetermined time dependent upon the shape of the cam surface providedthereon which engages with roller I26 and acts on pilot valve I6 throughoperating rods IN and IIII and the length of the opening gas blast isthereby controlled.

When closing of circuit breaker I0 is initiated through energization ofsolenoid 80, a counterclockwise rotation of bell cranks 22, 23, and 24and cam I25 results. A suitable cam surface provided on cam I25 willcause opening of pilot valve I8 through operating rods IOI' and IOI soas to provide a closing blast of fluid adjacent the approaching contactsof circuit breaker I0 at a predetermined point in the closing strokethereof.

The operation of my improved control and operating mechanism will now bedescribed briefly with reference to Fig. l which illustrates theapparatus at the instant the circuit breaker III has been closed andbefore piston 35 of fluid motor 33 has been returned to its initialposition by spring means 38. If the pressure in source 59 issufficiently high so that operation of circuit breaker I0 may safely beaccomplished, the interlock I I1, schematically shown in Fig. 1 andshown in detail in Fig. 5, doesnot interfere with the free movement oftrip'flnger IIB. If solenoid is energized in response to an abnormalcondition on the system which circuit breaker I0 protects, lever 96 isrotated causing lever 93 to remove the bias of spring 92 and allow pilotvalve 16' to open. Such operation of pilot valve I6 causes opening ofbalanced pressure valve 90, best shown in Fig. 3, whereupon fluid fromsource 59 is admitted through passage 9I to force piston 84 upwardly,thereby moving valve member 8| and interconnecting conduits 63 and I5.Rotation of lever 96 also opens tripping valve I06 so that, as soon asvalve I04 is opened upon slight movement of piston 84, fluid pressure isadmitted to pneumatic tripping means I01, causing rotation of tripfinger II6 as well as latch 52 so that trip-free mechanism 31 isreleased and circuit breaker I0 is opened under the operation of springmeans 29 and 30. It will be understood that, since valve member 8| wasmoved prior to the admission of fluid to pneumatic tripping means I01, ablast of fluid adjacent contacts II and I2 is assured before theinitiation of the opening movement of circuit breaker I0.

Even though solenoid 95 should be immediately deenergized, cam memberI25 will continue to hold pilot valve I5 and consequently blast valve 54open for a predetermined time, depending upon the cam surface providedon cam I25 so as to time the fluid blast adjacent contacts II and I2 andinsure interruption of the circuit. The

applied to cable I02 instead of energizing opening solenoid 95.

To close circuit breaker i0, it is necessary to energize closingsolenoid 80 through any suitable control circuit, whereupon balancedpressure valve 8! is opened to cause fluid motor 33 to provide thenecessary closing force for charging springs 29 and 80 and for closingthe contacts of circuit breaker l0. Since fluid motor 33 acts throughthe trip-free thrust-transmitting linkage 3i, circuit breaker i may beopened at any time during the closing stroke. Furthermore, cam I actingthrough rods [0| and [01 causes operation of blast valve 64 withoutefiecting tripping vaive I06 or pneumatic tripping means I01 so that ablast of fluid is provided adjacent contacts I i and i2 when the circuitbreaker is being closed. Since blast valve 64 is held open by virtue ofcam i25 during a portion of the closing stroke, highspeed trip-freeoperation may be obtained and a continuous supply of gas of circuitbreaker in under pressure adjacent contacts H and I! will be provided.

It will be apparent to those skilled in the art that my invention is notlimited to the particular construction shown but that changes andmodifications may be made without departing from the spirit and scope ofmy invention and I aim in the appended claims to cover all such changesand modifications.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, means for producing relativemovement between said contacts to open said circuit breaker, a source offluid under pressure, a blast valve associated with said source forproducing upon opening thereof a blast of fluid past the contactingportions of said contacts for arcextinguishing purposes during theopening movement of said circuit breaker, pneumatic means for initiatingthe opening movement of said circuit breaker, and valve means directlycontrolled by the opening movement of said blast valve for connectingsaid source and said pneumatic means to initiate the opening movement ofsaid circuit breaker only after a predetermined opening movement of saidblast valve.

2. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, means for producing relativemovement between said contacts, a source of fluid under pressure, avalve associated with said source for producing a blast of fluid pastthe contacting portions of said contacts for arc-extinguishing purposesduring both opening and closing movements of said circuit breaker, meansfor opening said valve in response to an abnormal current condition onthe power circuit associated with said circuit breaker prior to anyopening movement of said circuit breaker, pneumatic means for initiatingthe opening of said circuit breaker, means directly controlled by theopening movement of said valve for connecting said source and saidpneumatic means to initiate the opening movement of said circuit breakerafter a predetermined opening movement of said valve, and means formaintaining said valve in the open position until a predeterminedseparation of said relatively movable contacts has occurred.

3. In an operating system for an electric circuit breaker of thefluid-blast type comprising a plurality of relatively movable contacts,means for producing relative movement between said contacts, a source offluid under pressure, a blast valve associated with said source forproducing a blast of fluid past the contacting portions of said contactsfor arc-extinguishing purposes during both opening and closing movementsof said circuit breaker, a plurality of means for operating said valveprior to any opening movement of said circuit breaker, pneumatic meansfor initiating the opening movement of said circuit breaker, valve meansdirectly controlled by the openlng movement of said blast valve forconnecting said source and said pneumatic means to initiate the openingmovement of said circuit breaker only after a predetermined opening ofsaid blast valve has occurred, and means responsive to relative movementbetween said contacts for determining the closing instant of said blastvalve.

4. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, means for producing relativemovement between said contacts, a source of fluid under pressure, avalve associated with said source for producing a blast of fluid pastthe contacting portions of said contacts for arc-extinguishing purposesduring both opening and closing movements of said circuit breaker, meansfor opening said valve in response to an abnormal current condition onthe power circuit associated with said circuit breaker to produce saidblast of fluid past the contacting portions of said contacts prior toany opening movement of said circuit breaker, means for initiating theopening of said circuit breaker after a predetermined opening movementof said valve, and means for maintaining said valve in the open positionuntil a predetermined separation of said relatively movable contacts hasoccurred, said last-mentioned means being so constructed and arranged tocause opening of said valve at a predetermined point during the closingstroke of said circuit breaker.

5. In an operating system for an electric circuit breaker of thefluid-blast type comprising a plurality of relatively movable contacts,means for producing relative movement between said contacts, a source offluid under pressure, a valve associated with said source for producinga blast of fluid past the contacting portions of said contacts forarc-extinguishing purposes during both opening and closing movements ofsaid circuit breaker, means for opening said valve in response to anabnormal electrical condition occurring on the power circuit associatedwith said circuit breaker, manual means for opening said valve, andpneumatic means arranged to be connected to said source directly by theopening movement of said valve for initiating the opening movement ofsaid circuit breaker after a predetermined opening movement of saidvalve.

6. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, means for producing relativemovement between said contacts, latching means for holding said contactsin current-conducting engagement when said circuit breaker is in theclosed position, a fluid-operated plunger for releasing said latchingmeans, a source of fluid under pressure, a blast valve associated withsaid source for producing a blast of fluid past the contacting portionsof said contacts for arc-extinguishing purposes during the openingmovement of said circuit breaker, and valve means connected to saidblast valve and operable after a predetermined opening movement of saidblast valve for connecting said source with said fluidoperated plungerso that release or said latching means and consequent opening o t-saidcircuit breaker occur.

7. In an operating system for an electric circuit breaker comprising aplurality of relatively y last-mentioned means so that said first-men-.

tioned means may cause opening movement of said circuit breaker, asource of fluid under pressure, a piston-operated blast valve associatedwith said source for producing a blast of fluid adjacent said contactsfor arc-extinguishing purposes during the opening movement or saidcircuit breaker, a valve mounted on said piston and arranged to beopened after a predetermined opening movement of said blast valve forinterconnecting said source and said fluid-operated means so thatopening movement of said circuit breaker may occur only after theexistence of a blast of fluid for arc-extinguishing purposes adjacentsaid contacts.

8. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a fluid motor for producingrelative movement between said contacts, a source of fluid underpressure for operating said 'motor, means for interconnecting saidsource of fluid and said motor for closing said circuit breaker,energy-storage means for opening said circuit breaker so constructed andarranged as to be charged during the closing stroke of said circuitbreaker, means for restraining said energystorage means in the chargedcondition when said circuit breaker is in the closed position, trippingmeans for releasing said energy-storage means to open said circuitbreaker whereby highspeed opening of said circuit breaker is obtained,means including a blast valve for producing a blast of fluid adjacentsaid contacts for areextinguishing purposes during the opening movementof said circuit breaker, and pneumatic means for releasing said trippingmeans when a predetermined opening movement of said blast valve hasoccurred.

9. In an operating system-for an eleptric circuit breaker comprising aplurality of'relatively movable contacts, means for producing relativemovement between said contacts, a trip-free thrust-transmittingmechanism interposed between said last-mentioned means and saidrelatively movable contacts, means for holding said contacts incurrent-conducting engagement when said circuit breaker is in the closedposition, fluid-operated means for releasing said lastmentioned means sothat said first-mentioned means may cause opening movement of saidcircuit breaker, a source of fluid under pressure, a blast valveassociated with said source for producing a blast of fluid past thecontacting portions of said contacts for arc-extinguishing purposesduring the opening movement of said circuit breaker, and means foroperating said fluidoperated means only after a predetermined operationof said blast valve to insure a blast of arc-extinguishing fluid aroundthe contacting portions of said contacts upon separation thereof.

10. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a fluid motor for producingrelative movement between said contacts, a source of fluid underpressure for operating said motor, valve means for connecting saidsource of fluid with said fluid motor for closing said circuit breaker,means for opening said circuit breaker, a trip-free thrust-transmittingmechanism interposed between said fluid motor and said relativelymovable contacts, means including a blast valve associated with saidsource for producing a blast of fluid adjacent said contacts forarc-extinguishing purposes upon opening said circuit breaker, means forrestraining said tripfree mechanism to hold said circuit breaker in theclosed position, and pneumatic means for releasing said last-mentionedmeans to initiate opening of said circuit breaker only after apredetermined opening movement of said blast valve has occurred.

11. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, means for producing relativemovement between said contacts, latching means for holding said contactsin current-conducting engagement when said circuit breaker is in theclosed position, fluid-operated means for releasing said last-mentionedmeans so that said firstmentioned means may cause opening movement ofsaid circuit breaker, a source of fluid under pressure, a blast valveassociated with said source for producing upon opening thereof a blastof fluid past the contacting portionsof said contacts forarc-extinguishing purposes during the opening movement of said circuitbreaker, means for operating said fluid-operated means only after apredetermined opening of said blast valve to insure a blast ofarc-extinguishing fluid past the. contacting portions of said contactsupon separation thereof, and a mechanical interlock for rendering saidfluid-operated means ineflective when the pressure of said source fallsbelow a predetermined value.

12. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, a fluid motor for producingrelative movement between said contacts, a source of fluid underpressure for operating said motor, means for interconnecting said sourceof fluid and said motor for closing said circuit breaker, energy-storagemeans for opening said circuit breaker so constructed and arranged as tobe charged during the closing stroke of said circuit breaker, means forrestraining said energy-storage means in the charged condition when saidcircuit breaker is in the closed position, tripping means for releasingsaid energystorage means to open said circuit breaker whereby high-speedopening of said circuit breaker is obtained, a blast valve for producingupon opening thereof a blast of fluid past the contacting portions ofsaid contacts for arc-extinguishing purposes during the opening movementof said circuit breaker, pneumatic means for releasing said trippingmeans when a predetermined opening movement of said blast valve hasoccurred, and means for rendering said pneumatic means ineffective whenthe pressure of said source falls below that required for safe operationof said circuit breaker.

13. In an operating system for an electric circuit breaker comprising aplurality of relatively movable contacts, means for producing relativemovement between said contacts, latching means for holding said contactsin current-conducting engagement when said circuit breaker is in theclosed position, a fluid-operated plunger for releasing said latchingmeans, a source of fluid under pressure, means for connecting saidsource with said fluid-operated plunger to cause release of saidlatching means and consequent opening of s'aid circuit breaker, and amechanical interlock for preventing the release of said latching meanswhen the pressure of said source falls below a predetermined value.

14. In an electric circuit breaker of the fluidblast type comprising aplurality of relatively movable contacts, means for producing relativemovement between said contacts, a source of fluid under pressure, valvemeans associated with said source for producing a blast of fluidadjacent said contacts during both the circuit-interrupting and thecircuit-closing operations of said circuit breaker, means for preventingsaid first-mentioned means from operating prior to operation of saidvalve means, means for initiating the operation of said valve means, andmechanical means including a pivoted assembly interposed between saidvalve means and said means for producing relative movement between I

